For the treatment of acute and chronic liver failure, there is a critical need for both temporary and more permanent modes of liver support. Past biological approaches have been unsuccessful due largely to the inability to keep liver tissue functional in vitro for long periods. The long-term objective of the proposed research is to investigate and establish the factors that are necessary to maintain functional hepatocytes in vitro and to use these hepatocytes as the key components of an artificial liver system. The intended approach towards preservation of hepatocyte function is aimed at reconstitution of the histological organization of the liver from its isolated components and thereby reconstructing normal in vivo intercellular anatomic relationships in a culture system. Our preliminary results have indicated that, by simply sandwiching hepatocytes in between two layers of collagenous matrix, both morphology and protein secretory function are maintained for at least one month. The specific aims of our future studies are to: (1) characterize, in detail, the cell functions that have been preserved in this system (i.e. transcriptional rates, translational rates, enzymatic detoxification kinetics, gluconeogenic capacity); (2) study the effects of various perturbations on this culture system (i.e. changes in media composition, addition of other extracellular matrix components, addition of sinusoidal cells); (3) develop methodology for transplantation of these hepatocytes in the collagen sandwich configuration into a peritoneal cavity for temporary liver support in acute, reversible liver failure in animal models; and (4) design and construct a continuous culture perfusion system to evaluate the dynamic behavior of the cultured hepatocytes for use within an extracorporeal device in chronic long-term liver support in animal models. The principles developed in this work will provide a rational basis for the design of an artificial liver device for treatment of acute and chronic liver failure.